This invention relates to the art of rolling mills and, more particularly, to a modular transducer assembly for use in a rolling mill roll gap controlling system.
The transducer assembly of the present invention finds particular utility in conjunction with a hydraulic gauge control system for a four-high mill and which system includes relatively displaceable hydraulic piston and cylinder members through which force is applied to the upper back-up roll. Accordingly, the invention will be described with particular reference to such a mill and gauge control system; however, it will be appreciated that the invention can be utilized in other types of mills and in conjunction with relatively displaceable members of a roll gap controlling system other than force applying piston and cylinder members.
Generally, a four-high rolling mill utilizes large diameter screw-down roll positioning screws associated with the upper back-up roll chocks at the opposite ends of the upper back-up roll. The upper back-up roll chocks as well as the upper work roll chocks of the mill are vertically slidably supported in windows of the mill frame. The screw-down screws operate to position the upper back-up roll and thus the upper work roll relative to the lower work roll and lower back-up roll in accordance with the desired gauge for the material passing between the work rolls. Generally, a gauge control system is employed to determine relative displacement between the work rolls indicative of a variance from the desired gauge and to actuate appropriate roll adjusting mechanisms for adjusting the upper back-up roll and thus the upper work roll in accordance with such variances. In certain roll mill arrangements, the screw-down screws operate basically to position the upper back-up roll and thus the upper work roll relative to the lower work roll and lower back-up roll, and roll force is applied to the upper back-up roll by means of a hydraulic cylinder and piston unit interposed between each of the screw-down screws and the chock for the corresponding end of the upper back-up roll. In an arrangement of this character, hydraulic fluid under pressure is interposed between the piston and cylinder members, one of which bears against the lower end of the screw-down screw and the other of which bears against the top surface of the back-up roll chock, thus to apply the roll force necessary to roll material to the desired gauge. A variance in the gauge of the material passing between the work rolls of the mill causes relative displacement between the piston and cylinder members, and such relative displacement is employed to produce a control signal by which necessary adjustments can be made to maintain a desired predetermined roll gap between the work rolls. More particularly, a transducer assembly is employed between the piston and cylinder members to provide an output signal indicative of roll gap variations.
In conjunction with such a rolling mill having a hydraulic roll force applying arrangement, the piston and cylinder members are generally supported for removal from the roll mill frame for maintenance and for other purposes including maintenance or replacement of the transducer assembly mounted therebetween. Heretofore, transducer assemblies provided for use with hydraulic force applying arrangements have been linear transducer assemblies including relatively displaceable transducer components mountable in aligned openings in the piston and cylinder members. Such a transducer assembly includes a transformer coil and a core rod as the relatively displaceable transducer components and, heretofore, each of these components has been a structurally separate component assembled with respect to the other during sequential mounting thereof on the piston and cylinder members. In order to obtain optimum sensitivity with respect to response to variations in roll gap, the core rod component is in an extremely small diameter rod of piano wire dimension in cross section and, accordingly, is often bent during the assembly procedure when attempting to introduce the wire into the coil opening. Accordingly, the assembly procedure is not only tedious and time consuming, but often results in having to replace the component part carrying the core rod, thus further increasing assembly time and the assembly cost as a result of such part replacement. Still further, the relatively displaceable transducer components have a null or reference signal position relative to one another and previous transducer arrangements have required considerable time and effort to accomplish null positioning. In this respect, only one of the transducer components of such previous transducers is adjustable relative to the other, and the adjustment is only possible from the end of the piston and cylinder assembly facing the back-up roll chock. Therefore, when the hydraulic roll force applying assembly is removed from the roll mill frame and supported on a bench or the shop floor, the adjustable end of the assembly is not exposed. Accordingly, it is necessary to elevate or otherwise suitably support the roll force applying assembly to gain access to the underside thereof for null adjustment. If null adjustment is all that is required in connection with a maintenance procedure, such a special effort to achieve the adjustment is undesirably time consuming. Another disadvantage of such previous transducer arrangements resides in the fact that the structurally separate character thereof exposes the transformer coil and core rod to the adverse effects of the surrounding environment prior to assembly thereof on the piston and cylinder members and during any subsequent removal thereof from the piston and cylinder members.